This invention concerns locks, particularly cam locks as used on interior doors, panels, etc., including lockers for temporary use. The invention particularly relates to a mechanical combination lock that has an override mechanical key access, in a cam lock configuration.
Combination locks have been in several different styles, including those with a rotary dial and a combination consisting of a sequence of numbers that are entered after alternate rotations of the dial, such as right-left-right. Other combination locks have three or four or five rotatable dials, for example, which are turned by the user to set each at a particular digit to achieve access. Other forms of mechanical combination locks are also known.
Some of the locks can be used in a shared use application wherein the user sets a code to lock the door and scrambles the numbers and when he or she return sets the same code to unlock. In other applications the lock is used in an assigned mode wherein the user sets the correct code which is already set in the lock previously to open the lock.
These combination locks, including in the cam lock configuration, have sometimes included an override mechanical key access feature. In some cases the mechanical key cylinder with key slot has been located to extend through the knob or handle which the user ordinarily turns to release the cam lock after entering the necessary combination. In some cases the mechanical key cylinder is in the center of the knob and the knob simply wraps around the key slot. In other cases the knob covers the entire mechanical cylinder with the exception of the slot in the center for the insertion of the key. In this case the knob hides the key cylinder under the knob, and the key is inserted through the knob and into the cylinder.
The mechanical key would be held by a manager of a locker room in a gym facility or employer locker area, etc. Typically, manufacturers of such locks have provided only a few different key cut combinations for the mechanical override key for their various customers. Some manufacturers have produced only four different override key combinations; thus, a thief gaining access to a manager's override key would have a good chance of being able to open any locker in a different facility using the override key on locks from the same manufacturer.
Another problem with the typical combination lock/mechanical key override was that if the manager's override key was lost (or stolen), the lock would have to be dismantled in order to be re-keyed, which is costly and would have to be done on every lock.
There has been a need for a better, more conveniently and efficiently re-keyable mechanical override on a mechanical combination lock, particularly a cam lock.